Math is definitely challenging but what makes learning math fun and interesting is that, there are some tricks and techniques which can actually make the calculations easy to solve. Today, we will try to learn some math tricks which can be applied in solving different kinds of questions.
Multiplying a given number by 2
We all know the 2 times table. But what if 2 is being multiplied to a bigger number, there is a trick to make the multiplication quick and accurate. Think about it, multiplying by 2 it is nothing but doubling the given quantity. So to speed the calculations the given number can be added twice instead of multiplying by 2. For example 6 x 2 = 12.
This can also be got by 6 + 6 = 12. Now, if there is 32 x 2 = 64. This can also be got by 32 + 32 = 64.
Now applying this trick to bigger numbers multiplied by 2.
Find the value of 98340 x 2?
One method is the usual way of multiplying the given number by 2. But let us solve the same question with the trick of addition:
Hence 98340 x 2 = 1,96,680
— Tutor Pace (@TutorPace) August 4, 2015
Multiplying numbers which are multiples of 10
Did you know 10 is a very interesting number when it comes to multiplication? For example, in a question you come across a calculation such as 23 x 10 all you need to do is place a one zero next to 23. That is 23 x 10 = 230.
Can this be applied to bigger numbers as well? Yes it can! Let us look at some more examples:
While multiplying, 45 and 50 one method would be the regular multiplication. By applying the trick here all that needs to be done is 45 x 50, first find the value of 45 x 5 = 225. Since there is 50 which is a multiple of 10 place a zero next to 225.
So we get 45 x 50 = 2250. Another example would be, 25 x 30. Here first do 25 x 3 = 75. Now since there is 30 place a zero next to 75. This gives 25 x 30 = 750
Question: Sam brought 19 boxes of candies. Each box contains 200 candy bars, find the total number of candy bars in all the boxes.
Number of boxes of candies Sam brought is 19. Each box contains 200 candy bars.
Hence the total number of candy bars equal = 19 x 200.
Try to follow the diagram below for the calculation:
Multiplying a given number by 11
No matter what number is given to you multiplication with 11 can become quite simple, follow the trick here. Look at eleven, there are two 1’s. Now for example you have 14 x 11. First do 14 x 1 = 14 then to this add 140 which is 14 + 140 = 154?
So we get 14 x 11 = 154
Need a better idea? Follow the example below:
Find the value of 456 x 11?
Here first calculate 456 x 1 = 456 now add 4560 to it so you get 4560 + 456 = 5016
— Tutor Pace (@TutorPace) August 4, 2015
Adding three or more digit numbers
In some questions, you may have had situations where more than 2 numbers need to be added, it can get more tedious if they are big numbers. Let me share a little secret that can make adding such numbers much easier. For example there is a word problem: Riya spent $ 112 on shoes, $ 216 on bag and $315 on books. Find the total amount of money Riya spent on all the items. Solution: For the given question, the total amount of money spent equals the sum of all the given individual prices = $ 112 + $ 216 + $ 315. Follow the trick here, rather than adding the individual number. Add the hundreds place first. Follow the solution:
— Tutor Pace (@TutorPace) August 3, 2015
Squaring number ending in 5
This rule is applicable from 5 to 95 only (i.e., 5, 15, 25, 35, 45, 55, 65, 75, 65, 75, 85, 95.) and here is how it works! We have 5 x 5 = 25.
The trick is, for a number ending in 5 when squared always has to end in 25. So for a given number example 152 pick the tens place, which is 1. Now the number after 1 is 2. Multiply 1 x 2 = 2. Now place a 25 next to 2. We get 225.
Now for 25 x 25. Here, 2 is in the tens place. What is the number next to 2, 3. So do 2 x 3 = 6. Now place a 25 next to 6. We get, 25 x 25 = 625.
Let us follow the diagram for clarity, take 65 x 65.
Hence 65 x 65 = 4225
Divisibility rule for number 2
Here is a quick mental math trick to find weather a given number is divisible by 2 or not just by looking at it. If a number is ending with an even number then it is divisible by 2.
What are all the even numbers between 0 and 9 (0, 2, 4, 6, and 8).
Look at an example: 48 here 8 is an even number so it is divisible by 2. Now 51 is not divisible by 2 as 1 is an odd number. Apply the same for big numbers.
Find out if 4576 is divisible by 2? Prove it!
Here 4576 is ending with number 6. Since 6 is an even number the given number is divisible by 2. Follow the diagram for a quick check:
Divisibility rule for number 4
Now that you are familiar with the divisibility rule for 2. Let us quickly check the divisibility rule for number 4. When it comes to 4 always check whether the last 2 numbers are divisible by 4. Consider 324 here it’s clearly know that 24 is divisible by 4 so 324 will be divisible by 4. Now let me give you another example:
Find out whether 5608 is divisible by 4? Check your answer.
Here again use the trick and figure it your mind. 08 are the last two numbers of the given number. Since 08 is divisible by 4, 5608 is divisible by 4. Let’s check if we got it right look at the diagram below:
Divisibility rule for number 5
Did your math calculations get faster on the divisibility part? Now let us follow the trick for checking divisibility with number 5. For number 5, the given number should end either with 0 or 5. Take an example of 560 it is divisible by 5 since its ending in 0. Whereas 432 is not divisible by 5 since its ending with 2 not 0 or 5. Look at the following question.
Find out if 890 is divisible by 5? Check your answer.
Here the given number 890 is ending in 0, so it is divisible by 5. Let us check the answer, follow the diagram below:
Combining the like terms
Many students find adding and subtracting like terms very confusing. Let us look at a simple way of solving this kind of a question. Did you know there is a trick with which you can solve the combining like terms in your mind? Here is what can be done:
Consider a question for finding 5x + 6x.
A like term is a term which have the same variable. Here it is x. Now for adding 5x and 6x since x is the same, just find 5 + 6 = 11. Hence 5x + 6x = 11x.
Did you follow the solution? Follow the next example:
Find the value of 3x + 7x + 10x?
All that needs to be done is add the numbers and place the common variable x next to the sum. Take a look at the diagram below:
Hence the solution is 20x.
Therefore, practice these tricks and apply them in your math calculations. You will be amazed how they will aid in speeding your calculations. If you still need help, chat with a Live Math Tutor Online Now!